Heat exchanger structure

ABSTRACT

A vibration suppressing structural framework for tubular heat exchangers including retaining members cooperating with one another to restrain movement of the tubes.

ilnrted States Patent 11 1 1111 3,929,189 Lecon 1 Dec. 30, 1975 HEAT EXCHANGER STRUCTURE 3,420,297 1/1969 Romanos 122/510 x 3,545,534 12/1970 Coles 165/162 X [75] lnventor- Andrew Lem", Akron 3,575,236 4/1971 Romanos 165/162 [73] Assignee: The Babcock & Wilcox Company 3,677,339 7/1972 Perrin et a1, 122/510 X New York, FOREIGN PATENTS OR APPLICATIONS [22] Filed: Mar. 20, 1974 676,152 11/1929 France 248/68 R 21 A 1. No.: 452 859 1 pp Primary Examiner-Char1es .1. Myhre Assistant Examiner-Theophil W. Streule, Jr. [52] US. Cl. 165/69; 165/162; 122/510 Attorney, Agent, or Firm.]. Maguire; R. J. Edwards [51] Int. C1. F28F 7/00 [58] Field of Search 165/162, 678, 69, 81, 82;

122/510; 110/98 R; 248/68 R, 67 [57] ABSTRACT A vibration suppressing structural framework for tu- [56] References Cited bular heat exchangers including retaining members UNITED STATES PATENTS cooperating with one another to restrain movement of 1,430,769 10/1922 Thompson 165/162 the tubes 2,893,698 7/1959 Nunninghoff 122/510 6 Claims, 10 Drawing Figures Patent Dec. 30, 1975 Sheet 2 of 2 3,929,19

j FIG.4

HEAT EXCHANGER STRUCTURE BACKGROUND OF THE INVENTION The present invention relates to vibration resulting from combustion gases passing over a tubular heat exchanger and more particularly to a structural framework for suppressing vibration of the heat exchanger.

It is common practice in the design of a modern high capacity vapor generator to provide heat exchange surfaces in the form of closely spaced tubes positioned in a passage through which combustion gases at relatively high velocities are conveyed, with the tubes having portions thereof arranged in spaced parallel rows distributed transversely of the direction of gas flow. In this type of construction, it has been found that the passing of combustion gases over the transversely disposed tube portions causes gas flow instability that may give rise to large amplitude pulsations which are in acoustical resonance with the passage enclosure thereby causing severe vibration as well as intense noise. This condition has been aggravated by the present day trend toward high capacity vapor generators with its concomitants of increased gas mass flows and heat exchange surface which, coupled with the desirability for cost saving compact installations, have resulted in higher gas velocities and closer tube spacing, particularly for heat exchangers located in the lower gas temperature zones. The increase in gas velocities has given rise to vibrations of such severity as to cause the tubes of one row to oscillate and strike those of an adjacent row thereby endangering the physical structure of the heat exchanger.

SUMMARY OF THE INVENTION The present invention relates to a structural framework for suppressing vibration in tubular heat exchangers of the type having at least one bank of tube rows spaced across the gas stream in side-by-side parallel relation, with each row being formed of substantially coplanar return bend tube segments spaced in the direction of flow of the gas stream and wherein, in accordance with the invention, there are provided first and second retaining members, with the former being preferably in the shape of elongated flat bars and the latter being preferably flat bars of relatively short dimensions and having a T-shape configuration.

The first retaining members extend parallel to the flow of the gas stream, and are paired to contiguously straddle each of at least some of the heat exchanger tube rows, and have their respective ends projecting out from opposite sides of the tube bank. The first retaining members are drawn tightly against the straddled tube sections and are fixedly maintained in that position by having the ends, which project out of the same side of the bank, rigidly interconnected by tying members, the latter being preferably shaped as elongated flat bars.

The second retaining members are disposed transversely of the flow of the gas stream, and extend between tube segments of the straddled rows and have their respective stem portions extending through corresponding slots formed in the pairs of first retaining members straddling the tube rows. Each of the slots of first retaining members, located adjacent the head portion of second retaining members, and that segment of the stem portion which lies within the slot are sized to provide a press fit between at least one pair of mating surfaces. The slots of the remaining first retaining members are preferably oversized with respect to the segment of the stem portion extending therethrough and have at least one pair of adjoining surfaces rigidly connected to one another.

BRIEF DESCRIPTION OFTHE DRAWINGS FIG. 1 is a sectional side elevation of a vapor generating and superheating unit' including a heat exchanger embodying the present invention.

FIG. 2 is a side view of the heat exchanger and the vibration suppressing structural framework related thereto.

FIG. 3 is an enlarged sectional end view taken along line 33 of FIG. 2, and fragmented for clarity.

FIG. 4 is a fragmentary detailed end view of the arrangement of first and second retaining members with respect to heat exchanger tube sections.

FIG. 5 is a fragmentary detailed side view of a first retaining member disposed adjacent the respective head portions of related second retaining members.

FIG. 6 is a fragmentary detailed side view of a first retaining member disposed adjacent the distal end of respective stem portions of related second retaining members.

FIG. 7 is a plan view of a second retaining member in accordance with an embodiment of the invention.

FIG. 8 is a side view of the second retaining member of FIG. 7.

FIG. 9 is a plan view of an alternate embodiment of a second retaining member.

FIG. 10 is a side view of a further alternate embodiment of a second retaining member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. I, there is shown a vapor generating and superheating unit 1(1 including water cooled walls 12 which define a furnace chamber or combustion space 14 to which a fuel and air mixture is supplied by burners as schematically shown at 16. After combustion has been completed in the furnace chamber 14, the hot gases flow upwardly around the nose portion 18, over the secondary superheater 20, and thence downwardly through the convection pass 22 containing the primary superheater 24 and the economizer 26. The gases leaving the convection pass 22 flow through an air heater (not shown) and :are thereafter discharged through a stack (not shown). It will be understood that in accordance with well known practice, the superheaters and economizer include banked rows of return bend tube segments extending across the width of their corresponding gas pass and arranged for fluid flow therethrough and in indirect heat exchange with the combustion gases flowing through the pass.

The vapor generating surface is top supported by structuraltnembers including upright members 28 and cross beams 30, from which hangers 32, of which only a few are illustrated, support the walls, heat exchangers and other related par-ts of the vapor generating and superheating unit.

The economizer includes an. upper and a lower bank, both of which are upheld by support rods 34 which transmit the economizer weight load to primary superheater stringer tubes 36 which are in turn supported by hanger rods 32. In accordance with the invention, the economizer is provided with vibration suppressing 3 structural frameworks as shown at 38.

Referring to FIG. 2, there is shown a sectional side view of the heat exchanger in the form of economizer 26, and including an inlet and outlet header, 40 and 42, and a plurality of bent tubes 44 connected therebetween. Each tube 44 includes generally upright inlet, intermediate and outlet leg segments, 46, 48 and 50, and vertically spaced, horizontally extending return bend segments 52 and 54 disposed therebetween and forming separate upper and lower banks, 56 and 58. The economizer 26 is supported by rods 34 which may be in the form of bars 60 paired to straddle superposed tube rows of the upper and lower banks, 56 and 58 and including saddle supports (not shown) disposed between each pair of bars 60 to support one or more return bend tube segments 52 and 54. The flat bars 60 are rigidly interconnected at their respective upper and lower ends by tie bars 62 and include support plates 64.

In accordance with the invention, there are provided a plurality of flat bars 66 arranged in spaced groups wherein the bars 66 in each group are rigidly interconnected at their respective upper and lower ends by tie bars 68 to form the vibration suppressing structural framework 38 hereinafter described.

Referring to FIG. 3 there is shown a fragmented partial end view of the economizer bank 58 having a plurality of spaced tube rows 70 arranged in side-byside parallel relation, with each row being formed of spaced coplanar return bend tube segments 54, and including a vibration suppressing structural framework comprising pairs of first retaining members or elongated flat bars 66 straddling tube rows 70, and second retaining members or short flat bars 72 extending between tube segments 54 in the straddled rows.

The first retaining members 66 are drawn tightly against the tube segments 54 of the straddled tube rows and are fixedly maintained in that position by having the ends, which project out of the same side of the bank 58, rigidly interconnected by tying members of flat tie bars 68 which are preferably welded to respective ends of the members 66.

The second retaining members 72 are positioned in spaced relation to the straddled return bend tube segments 54 and extend through aligned slots formed in the pairs of first retaining members straddling the tube rows 70. The second retaining members 72 are fixedly secured to corresponding pairs of first retaining members 66 to further insure that the latter remain tightly drawn against the straddled tube segments 54 and to form a framework therewith which preserves the spacing between tube segments 54 and prevents direct contact between adjoining tube surfaces.

Referring to FIG. 4, there is shown a detailed view of the assembled framework including first retaining members 66 drawn tightly against the tube segments 54 and slotted to receive respective stem portions 78 of second retaining members 72 which are press fitted thereinto at one end and welded thereto at the opposite end as shown at 74.

Referring to FIG. 5, there is shown a detailed side view of a typical first retaining member 66 situated adjacent respective head portions 76 of second retaining members 72 whose stem portions 78 extend through slots 80 in the member 66 and through the spacing between tube segments 54. In accordance with the invention, the slots 80 are formed with one or more of their dimensions being of lesser magnitude than a corresponding dimension of that segment of the stem portion 78 which extends therethrough. Mechanical force is applied when inserting the second retaining member 72 through the slot and a press fit is achieved between at least one pair of mating surfaces. The slot 80 depicted in the drawing is of trapezoidal configuration and is sized so that the shorter of its parallel sides has a dimension of lesser magnitude than that of either of the longer parallel sides taken along the rectangular cross section of that segment of the stem portion 78 lying adjacent the head portion 76 of a second retaining member 72. The longer of the parallel sides of slot 80 is substantially equal in magnitude to the longer parallel sides taken along the aforementioned cross section. It will be understood that the slot 80 configuration will vary so as to accommodate a particular stem 78 configuration while achieving a press fit therebetween.

Referring to FIG. 6, there is shown a detailed side view of a typical first retaining member 66 situated adjacent the distal end of respective stem portion 78 of second retaining members 72 which extend through the spacing between tube segments 54 and through slots 82 in the member 66. In accordance with the invention, the slots 82 are formed with their cross sectional dimensions being of greater magnitude than the corresponding dimensions of that segment of stem portion 78 which extends therethrough. A weld .74 is effected between at least one pair of adjoining surfaces of the stem 78 and retaining member 66. The cross sectional dimensions of the slots 82 are deliberately oversized in order to facilitate the assembly of the vibration suppressing framework.

Referring to FIG. 7, there is shown a plan view of an embodiment of a second retaining member 72 having a head portion 76 and a stern portion 78, and wherein the latter includes a shoulder 77 connected to or, merging with, the head portion 76, and a shank 79 extending from the distal end of the shoulder 77. The cross section of shank 79 is sized and shaped to substantially match the corresponding dimensions and configuration of the slot 80 formed in the retaining member 66 situated adjacent the head portion 76. In accordance with the invention, the shoulder 77 has a cross section which may be of different configuration and whose one or more dimensions are of greater magnitude than the corresponding dimensions of the slot 80, so as to achieve a press fit between assembled first and second retaining members 66 and 72.

Referring to FIG. 8, there is a side view of the second retaining member 72 of FIG. 7 comprising the head portion 76 and the stem portion 78 with its shoulder 77 and shank 79.

Referring to FIG. 9, there is shown a plan view of an alternate embodiment of a second retaining member 72 having a head portion 76 and a stem portion 78A, the latter extends through a pair of first retaining members 66 tightly straddling a tube segment 54. The instant retaining member 72 differs from the embodiment of FIGS. 7 and 8 in that the width of its stem portion 78A is uniformly tapered in the direction away from the head portion 76. The stem width dimension adjacent the head portion 76 is greater than the corresponding dimension of the retaining member receiving slot 80, so as to achieve a press fit between assembled first and second retaining members 66 and 72. The cross sectional dimensions of slot 82 of the retaining member 66, situated at the distal end of stem portion 78A, are

greater than the corresponding dimensions of the stem portion extending therethrough so as to facilitate assembly of the framework.

Referring to FIG. 10, there is shown a side view of a further alternate embodiment of a second retaining member 72 comprising a head portion 76 and a stem portion 78B. The instant retaining member 72 differs from the embodiments of FIGS. 7, 8 and 9 in that the thickness of its stern portion 783 is uniformly tapered in the direction away from the head portion 76. The stem thickness dimension adjacent the head portion 76 is greater than the corresponding slot dimension of the retaining member normally situated adjacent the head portion 76.

While in accordance with provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A tubular heat exchanger disposed within a passageway, means for conveying a heated fluid stream over the heat exchanger and means for passing a fluid to be heated through the heat exchanger, said heat exchanger having at least one bank of spaced tube rows arranged across the fluid stream in side-by-side parallel relation, each of the rows being formed of substantially coplanar return bend tube segments spaced in the direction of flow of the fluid stream, and means for suppressing vibration of the heat exchanger, said last named means including rigidly connected first and second intersecting plate members, wherein first plate members are paired to contiguously straddle each of at least some of said rows, and second plate members are spaced from and extend between return bend tube segments of said straddled rows, the first plate members being slotted to accommodate the substantially perpendicular extension there'through of intersecting second plate members, and said second plate members being press fit into respective slots of at least one of the first plate members intersecting therewith.

2. The tubular heat exchanger according to claim 1 wherein respective ends of the first plate members protrude from opposite sides of the tube bank and including tying plate members rigidly interconnecting the ends protruding on the same side of said bank.

3. The tubular heat exchanger according to claim 1 wherein the slots in at least one of each of the paired first plate members are each formed with at least one dimension of lesser magnitude than the corresponding dimension of that portion of second plate member to lie within the slot.

4. The tubular heat exchanger according to claim 1 wherein said second plate members are weldably connected to at least one of the first plate members intersecting therewith.

5. The tubular heat exchanger according to claim 1 wherein said first and second plate members are of rectilinear configuration.

6. The tubular heat exchanger according to claim 1 wherein each of said second plate members is a T- shaped bar having a tapered stem. =l= 

1. A tubular heat exchanger disposed within a passageway, means for conveying a heated fluid stream over the heat exchanger and means for passing a fluid to be heated through the heat exchanger, said heat exchanger having at least one bank of spaced tube rows arranged across the fluid stream in side-by-side parallel relation, each of the rows being formed of substantially coplanar return bend tube segments spaced in the direction of flow of the fluid stream, and means for suppressing vibration of the heat exchanger, said last named means including rigidly connected first and second inTersecting plate members, wherein first plate members are paired to contiguously straddle each of at least some of said rows, and second plate members are spaced from and extend between return bend tube segments of said straddled rows, the first plate members being slotted to accommodate the substantially perpendicular extension therethrough of intersecting second plate members, and said second plate members being press fit into respective slots of at least one of the first plate members intersecting therewith.
 2. The tubular heat exchanger according to claim 1 wherein respective ends of the first plate members protrude from opposite sides of the tube bank and including tying plate members rigidly interconnecting the ends protruding on the same side of said bank.
 3. The tubular heat exchanger according to claim 1 wherein the slots in at least one of each of the paired first plate members are each formed with at least one dimension of lesser magnitude than the corresponding dimension of that portion of second plate member to lie within the slot.
 4. The tubular heat exchanger according to claim 1 wherein said second plate members are weldably connected to at least one of the first plate members intersecting therewith.
 5. The tubular heat exchanger according to claim 1 wherein said first and second plate members are of rectilinear configuration.
 6. The tubular heat exchanger according to claim 1 wherein each of said second plate members is a T-shaped bar having a tapered stem. 